Blood coagulation factor IX (F9) involved in hemostatic coagulation is an essential blood coagulation factor which has been known since a long time ago, and is well known as a causative protein for hemophilia. During the process of coagulation reaction, F9 is activated by being cleaved with blood coagulation factor XI (F11) into two fragments (heavy and light chains) and so on, and thereby promotes the coagulation reaction. In F9, its important segment functioning as a blood coagulation factor is the C-terminal (heavy chain) trypsin domain, whereas the functions of its N-terminal (light chain) segment have not been well known.
Clots formed by blood coagulation are composed of various proteins including blood coagulation factors. Previous studies have confirmed that neovascularization is more likely to occur within clots and that cancer patients with thrombosis have high risk of cancer metastasis (see, e.g., Non-patent Document 1; Gerotziafas G T et al., Clinical studies with anticoagulants to improve survival in cancer patients. Pathophysiol Haemost Thromb., 2008, vol. 36(3-4), p. 204-11). However, no certain conclusion has been reached as to the mechanisms or key molecules responsible for these events. Based on the statistically demonstrated relationship between clots and cancer metastasis, some attempts have been made to suppress cancer metastasis by administration of anticoagulants, and significant suppression of cancer metastasis has been confirmed. However, the use of anticoagulants is associated with the risk of bleeding, and hence there is a limit on the amount of their usage. Moreover, anticoagulants have not yet been widely used because they are empirically known to be effective but the mechanism of their action remains unknown.
On the other hand, cell migration is an essential event in the vital activities of the human body and is involved in a wide range of events occurring in the human body, while it is also known to cause unfavorable results including cancer metastasis. In addition, other known events in which cell migration is involved include angiogenesis and wound healing, etc.